500 Internal Server Error

The server encountered an unexpected condition which prevented it from fulfilling the request.

Traceback (most recent call last):
  File "E:\Downloads\Download applications\Sick-Beard\cherrypy\_cprequest.py", line 660, in respond
    response.body = self.handler()
  File "E:\Downloads\Download applications\Sick-Beard\cherrypy\lib\encoding.py", line 193, in __call__
    self.body = self.oldhandler(*args, **kwargs)
  File "E:\Downloads\Download applications\Sick-Beard\cherrypy\_cpdispatch.py", line 25, in __call__
    return self.callable(*self.args, **self.kwargs)
  File "E:\Downloads\Download applications\Sick-Beard\sickbeard\webserve.py", line 1409, in processEpisode
    result = processTV.processDir(dir, nzbName)
  File "E:\Downloads\Download applications\Sick-Beard\sickbeard\processTV.py", line 120, in processDir
    returnStr += logHelper(u"Processing failed for "+cur_video_file_path)
  File "E:\Downloads\Download applications\Sick-Beard\sickbeard\processTV.py", line 34, in logHelper
    logger.log(logMessage, logLevel)
  File "E:\Downloads\Download applications\Sick-Beard\sickbeard\logger.py", line 176, in log
    sb_log_instance.log(toLog, logLevel)
  File "E:\Downloads\Download applications\Sick-Beard\sickbeard\logger.py", line 144, in log
    self._rotate_logs()
  File "E:\Downloads\Download applications\Sick-Beard\sickbeard\logger.py", line 128, in _rotate_logs
    os.rename(cur_file_name, self._log_file_name(i+1))
WindowsError: [Error 32] The process cannot access the file because it is being used by another process